Meloxicam (4-hydroxy-2-methyl-N-(5-methyl-2-thiazolyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide) is an active substance which belongs to the group of NSAIDs (non-steroidal-anti-inflammatory drugs). Meloxicam and the sodium and meglumine salt thereof (N-methyl-D-glucamine salt) are described in EP-A-0 002 482. EP-A-0 002 482 shows, inter alia, the example of a 0.2% injectable solution of meloxicam consisting of the meglumine salt of the active substance, sodium chloride and water.
EP-A-0 945 134 discloses the pH-dependent solubility characteristics of meloxicam and its salts, i.e. the sodium salt, the ammonium salt and the meglumine salt, in aqueous solution. According to this, meloxicam is an active substance which does not dissolve readily in water. The meloxicam salts, particularly the meglumine salt, exhibit improved solubility as the pH increases between 4 and 10, as shown in Table 1 of EP-0 945 134. However, up till now it has only been possible to produce stable, clear, aqueous solutions with a low concentration of meloxicam. In addition to the in situ formation of a meloxicam salt, e.g. meglumine salt, and the addition of solubilisers, these solutions were required to have a pH in the range of maximum possible solubility as well as being reasonably well tolerated and contain a high proportion of organic solvent. Attempts to produce formulations with the same or a similar recipe led to cloudiness of the solution, e.g. if the meloxicam concentrations were higher, e.g. 2%.
WO9959634 A1 describes an eye drop solution containing 0.5% meloxicam but makes no reference to possible meloxicam concentrations over 1%. A commercially available 0.5% meloxicam solution is used in small animals such as dogs, heifers and calves to treat respiratory diseases and inflammation, for example.
An active substance for needleless injection makes it possible for the animal keeper himself to administer a sterile solution to the animal. The requirements imposed on an active substance solution for needleless injection include inter alia small injectable volumes, the possibility of weight-related dosage and maximum possible flexibility in the number of actuation processes per treatment unit. Accordingly, injection volumes of 50 μl per actuation, for example, are technically feasible. For this purpose, as described in DE10010123 A1, a sterile solution may be transferred under aseptic conditions into a sterile cartridge which is then inserted in the metering system.
It has not hitherto been possible to treat large farm animals with a meloxicam solution that could be injected without a needle. The low concentration of active substance in the injectable solution did not allow an acceptable, well tolerated injection volume. The administration of meloxicam solutions by needlefree injection requires that the solution be free from particles, as solutions of this kind are subject to the same requirements as solutions for parenteral administration. In addition to intracutaneous and subcutaneous administration transcutaneous administration should also be taken into consideration, involving administering the substance directly into the blood vessels. This latter route is directly comparable with intravenous administration by injection through a syringe. The method of administration by needle-free injection has a relevant effect on bioavailability, which will be greater than with intracutaneous or subcutaneous administration, as transcutaneous absorption also takes place with needle-free injection. Organic solvents, solubilisers and water-soluble substances can only be used in certain concentrations for reasons of drug tolerance. The problem of the present invention is to produce particle-free highly concentrated meloxicam solutions which are stable over long periods, which are suitable for needleless injection.